Hi bestoftherapy, I assume you're referring to the "Call phone with voice reminder" type. There's also an option (on the Content) tab for popup reminders to do text-to-speech.

The voice phone reminder uses SMS Matrix (http://www.smsmatrix.com) to call the phone numbers specified for the reminder recipients. A computer voice will speak what is entered under "Voice Reminder Template" for the reminder. The default is "Hello [Recipient]. This is an automated reminder. [Title], [When].", where the values in brackets are dynamic and get replaced with values for whichever event and recipient is being processed. You can edit the template as needed.

If you're asking how to get your business phone number to show up on the recipient's caller ID, I believe that might be possible by specifying your phone number in your SMS Matrix account settings. Log into your account on the SMS Matrix webpage and click "Settings" to access your account settings. Under "Account Info", enter the phone number you'd like to use for called ID in the "Your phone" field. If the phone number doesn't show up on caller ID, please contact SMS Matrix for support.https://www.smsmatrix.com/contact